Found my notes for the last WL Y-intake I opened up:
Id: 33.0mm/1.299 inch
Od: 36.1mm/1.421inch, this is the spigot cut for the PEEK seals
Throat 35.2mm/1.386inch. Have installed a 36 Mikuni VM on this bike.
Did braze to add to the thickness just for safety, although I never cut into it from the inside.